On Wed, 2008-03-26 at 17:07 +0100, Christian Ehrhardt wrote: > Hollis Blanchard wrote: > > On Tue, 2008-03-25 at 14:45 +0100, Christian Ehrhardt wrote: > >> => from one not yet defined point our guest seems to receive absolutely > >> nothing > >> => when the guest is hanging it sends nfs requests which are seen > >> externally, but it does not seem to get the respones > >> => the arp requests for the guest are repeated - maybe we can add some > >> very verbose debug in the guest virtio code and activate it when we see > >> that it is already hanging > >> => ideas: > >> - maybe some buffer/memory runs out and so incoming packets won't be > >> received anymore > >> - we break something in virtio / incoming interrupts (or maybe a lock) > >> and from that point no receive is possible > >> > > Could we be missing interrupts? Can you add a guest kernel timer that > > calls virtio_poll() regularly? > > > Working but not the final solution. > Preliminary workaround patch attached > > Atm I think we might disable interrupts and polling at the same time.
For disabled interrupts you mean that the VRING_AVAIL_F_NO_INTERRUPT flag is set or really your s390 replacement to cli? If it's just the flag you can ignore it in the host (virtio-net.c). btw: I didn't see any VRING_USED_F_NO_NOTIFY on the guest side. It is only for optimizations so just put it on your todo list. > > Good message: it was slow, but I saw a login prompt ;-) > here a guest "cat /proc/cpuinfo" > cat /proc/cpuinfo > processor : 0 > cpu : unknown (00000000) > clock : 666.666660MHz > revision : 0.0 (pvr 0000 0000) > bogomips : 2490.36 > timebase : 666666660 > platform : Bamboo > > That means once we found the reason for that staving virto-net device we > should have a basic working linux guest. > > P.S. added [email protected] (this time) to get any > virtio-net related suggestions from there too > > plain text document attachment (virtio-net-poll-on-timer) > Subject: [PATCH] kvmppc virtio-net: workaround for lost interrupt/polling > > From: Christian Ehrhardt <[EMAIL PROTECTED]> > > This patch is (atm) just a debug workaround. The issue is that virtio-net > works fine for a while but then "something" happens and we see neither > vp_interrupts nor calls to virtnet_poll anymore. > Looking at the network traffic shows that the kvm guest still sends packets > via virtio-net and that userspace tries to deliver things to the guest, but > the guest receives nothing. > Somehow it loks loke polling and interrupts are disables (more debugging > needed). > For now anyone can continue with that workaround patch (which is > very slow, I had no time to tune the polling interval yet). > There's an ugly fixme, but I don't yet know what exactly causes this BUG() > to trigger so thats the way to get it out for now. > I'll update the patch once I have an improved version. > > Signed-off-by: Christian Ehrhardt <[EMAIL PROTECTED]> > --- > > [diffstat] > virtio_net.c | 36 ++++++++++++++++++++++++++++++------ > 1 files changed, 30 insertions(+), 6 deletions(-) > > diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c > --- a/drivers/net/virtio_net.c > +++ b/drivers/net/virtio_net.c > @@ -194,17 +194,22 @@ again: > received++; > } > > + > /* FIXME: If we oom and completely run out of inbufs, we need > * to start a timer trying to fill more. */ > if (vi->num < vi->max / 2) > try_fill_recv(vi); > > - /* Out of packets? */ > - if (received < budget) { > - netif_rx_complete(vi->dev, napi); > - if (unlikely(!vi->rvq->vq_ops->enable_cb(vi->rvq)) > - && netif_rx_reschedule(vi->dev, napi)) > - goto again; > + /* FIXME - fails when called by workaround timer polling (sometimes) */ > + if (budget != 42) > + { > + /* Out of packets? */ > + if (received < budget) { > + netif_rx_complete(vi->dev, napi); > + if (unlikely(!vi->rvq->vq_ops->enable_cb(vi->rvq)) > + && netif_rx_reschedule(vi->dev, napi)) > + goto again; > + } > } > > return received; > @@ -294,6 +299,17 @@ again: > return 0; > } > > +static struct timer_list viopoll_timer; > +static void virtio_poll_wrap(unsigned long dev) > +{ > + struct virtnet_info *vi = netdev_priv((struct net_device *)dev); > + /* poll more often if polling received something */ > + if (virtnet_poll(&vi->napi, 42)) > + mod_timer(&viopoll_timer, get_jiffies_64() + (HZ/150)); > + else > + mod_timer(&viopoll_timer, get_jiffies_64() + (HZ/25)); > +} > + > static int virtnet_open(struct net_device *dev) > { > struct virtnet_info *vi = netdev_priv(dev); > @@ -308,12 +324,20 @@ static int virtnet_open(struct net_devic > vi->rvq->vq_ops->disable_cb(vi->rvq); > __netif_rx_schedule(dev, &vi->napi); > } > + > + // DEBUG (Missing interrupts ?) > + setup_timer(&viopoll_timer, virtio_poll_wrap, (unsigned long)(dev)); > + mod_timer(&viopoll_timer, get_jiffies_64() + HZ); > + printk("%s - set up virtnet_poll timer\n", __func__); > + > return 0; > } > > static int virtnet_close(struct net_device *dev) > { > struct virtnet_info *vi = netdev_priv(dev); > + > + del_timer(&viopoll_timer); > > napi_disable(&vi->napi); > > > _______________________________________________ > Virtualization mailing list > [email protected] > https://lists.linux-foundation.org/mailman/listinfo/virtualization _______________________________________________ Virtualization mailing list [email protected] https://lists.linux-foundation.org/mailman/listinfo/virtualization
